I think I'm having a brain fart, but someone help me here. I'm looking at Nordhaus' Nobel Prize slides, but I'm lost on slide 8. It has T <= 2C 100 yr average of $130, and T <= 2C of $225. What is the difference between these?

Saving is generally good for the economy. The exception is during recessions, when increases in demand boost the economy. But during those instances, we usually like to build bridges and schools instead of going around breaking people's things.

Kelton: Inflation is the relevant risk, not the size of the annual deficit

Anyway, if you are only interested to take cheap shots at MMT take it somewhere else. I'm not even a proponent, I'm just interested in improving my understanding and you are decidedly not helping in this.

That article isn't wrong (though it is something of an optimistic outlook), but I think it is very misleading. The authors admit they are separating out the macroeconomic framework of MMT, and leaving the "other" components out. While I believe they more or less described the macro framework correctly, those other components are - for all intents and purposes - part of MMT. Because of this, I believe that article paints a very incomplete picture of what most MMT proposals actually look like. Most criticisms, both here and elsewhere, focus on those other components (which I believe to be the source of your confusion).

I don't know how familiar with economics you are, so I'll lean on the safer side and explain things where I can. In economics, there is a very basic principle called "Long Run Money Neutrality" (LRNM). It just means that in the long run, issuing money will turn into inflation on a 1:1 basis and that money issuing has no impact on the real economy (we can't grow our economy just by printing more money). This has decades of both theory and empirical evidence behind it, and it almost universally accepted among mainstream economists (and even many heterodox ones as well!). Just for a very quick look over the evidence, Robert Lucas summarized much of the evidence around money neutrality in his 1995 Nobel Prize speech (his Nobel-Prize winning work was closely connected to money-neutrality), this post (all hail Inty) goes over a large body of evidence, and McCandless-Weber 1995 here in specific analyzed 110 countries as just one example of a good paper on this. I won't be spending any more time on this because this is just beating a dead horse by now, but this theory becomes important later.

So, once you break down the MMT model a bit you can see how it works. Monetary policy no longer used - fiscal policy is now the required tool to bring the economy to full output without overheating. This is more or less agreed upon by MMTers and the mainstream, and is described in your linked article.

Now a common criticism of the MMT model you have heard is that the money-issuing involved will lead to inflation. And this is entirely true, recall back to LRNM - it has to (on a 1:1 level). Of course, MMTers admit inflation is a concern (just like Kelton said), and they point to taxes as the solution. Except in this case, taxes are not being used to collect funds, they are being used to remove currency from circulation and destroy it. This means the government is no longer constrained by its willingness to tax, it's now constrained by how much inflation you're willing to tolerate. So up to this point, MMT has swapped the tax constraint for the inflation constraint.

The thing is, we found some time ago out that high and unstable inflation have large, negative (sometimes catastrophic) costs that we really like to avoid (the Fed explains further here). Sure, mainstream economists might quibble slightly at the optimal rate of inflation (some arguing 0%, while others argue it's as high as 4%), but they ultimately all agree it needs to be low and stable.

This is where many people - myself included - say the MMT framework doesn't add anything all that interesting under our standard understanding. With inflation considerations in mind, MMT has a very specific trade-off: taxes or inflation. So unless you admit you're going to let inflation run wild, you're left with...taxes again (and a whole lot of them). Given inflation as a practical constraint, you're stuck right back in the initial situation where you have to tax. Paul Krugman has a very brief (and easy to understand) article on MMT here. I have no doubt MMTers nitpicked the shit out of it (it was a 2 minute column after all) but the point is very simple. You can't finance any large portion of your budget through money-issue, or you end up with a lot of inflation. Krugman thinks trying to fund much of your budget through money-issue would quite likely lead to hyper-inflation. It should also be noted the US already engages in seigniorage - Federal Reserve profits are sent to the Treasury (many other countries do this too). Last year, those profits totaled about $80 Billion (less than 2% of the current fiscal budget). But you can read more about that topic here from the Fed if you want. Under this scope, the implications of MMT becomes quite boring (and I fail to see the appeal). Now here is where I find those "other components" become very important.

Most MMT proponets reject LRNM (many do so very openly, some implicitly) - it's basically a central part of MMT. They believe that this money-issuing can increase the real economy - and thus money-issuing becomes a more viable form of funding. Sure, they recognize some inflation might happen, but they don't really see it as much of an issue. Kelton's comments on the Planet Money podcast (talking about inflation):

Well, where is it? We've been doing it. We just did it with a $1.5 trillion tax cut. We did it with the $300 billion in additional spending. We've done it and done it and done it. Where is the inflation problem? I don't see it in the UK. I don't see it in Japan. I don't see it in the US.

This comment legitimately perplexes me. Fiscal policy doesn't determine inflation rates - monetary policy does. When fiscal policy becomes more expansionary, the Fed just counters. That's what monetary offset is. All those countries have independent central banks very good at hitting (or coming close to) their inflation targets. I would expect their inflation to remain 2% (within a small margin of error) regardless of what fiscal policy does.

(Perhaps they'll argue we haven't seen the inflationary pressures we expected - perhaps. There are a few reasons for this, but I have no idea how Kelton would think any of them are of assistance to her here).

MMTers also usually have a theory of economic growth that you have to run large fiscal deficits even in times of full output. They view a smaller deficit, or a surplus, as inherently harmful to growth. This is obviously contrary to virtually all of our evidence. Don't even listen to me - when MMT economist Jamie Galbraith promoted this idea in a speech, he freely admits 250 economists in attendance laughed at him.

Now, I could discuss the multiple reasons why I think even the MMT framework by itself (separated from all other components and programs, just as your linked article describes it) is a truly terrible idea, but I actually think those reasons come second to the problems around some of their other ideas.

I suggest MIT Courseware, but I admit I've never tried it on mobile. Look for an intro to micro and an intro macro course (in that order), that should teach you the basics. Consider getting textbooks too (search online for a PDF if you don't want to pay for it). I like Mankiw, but any standard intro textbook will do, it doesn't really matter.

I'm not sure if you're specifically referring to the United States or other countries as well, but I'm pretty sure the US already has some of the most school days in the year and a relatively long school day.

There is a good paper here that explains through some of the nuances and literature around Border Carbon Adjustments (BCA). How the BCA is designed has a large impact on how efficient it will be. There are a few issues that come up around BCA's - I'll go through some briefly, but the paper provides more detail and citations.

Firstly, we have an issue of information. If you're going to count for carbon emissions on the firm-level or product-level, how accurate will this process be? The more accurate it is, the more effective the BCA will be. However, the more detailed the process to determine this, the more complex this program becomes to administer (and possibly, adding barriers to trade as well).

Secondly, at one recent paper - McKibbin et al (2018) from the Stanford EMF 32 - finds a BCA would have currency distortion effects. The implication here being, that a BCA should be kept sufficiently limited, or net exports will be lower.

Lastly, it's a contested issue about the magnitude of impact BCA's would have. Largely depending on how they are designed, some research has argued they would be complex and uncertain, but ultimately wouldn't change much (this would likely be more likely to be true at lower carbon prices). This all becomes more uncertain in designing a BCA that would be legal under the WTO (but I'm not the right person to ask about the specifics of this).

There are other solutions to consider as well. Some placed have used output-based allocation systems on emissions-intensive, trade-exposed industries (you can see CCIR in Alberta as an example of this) to mitigate leakage. These systems aim to mitigate concerns of leakage or competitiveness by being more flexible, and providing rebates to producers (while still maintaining incentive to reduce emissions). I likely lean towards thinking output-based allocation systems offer the preferable solution, but that's just my opinion.

If even just a handful of major economies do this, it seems like a good way to enforce carbon restrictions globally, without relying on countries following an "honor system" that other agreements entail.

This part is where it can become more tricky. It depends what your goals are; if your goal is to reduce emissions leakage, then an output-based allocation system is a plausible alternative. If your goal is to pressure other countries into action, then a BCA might work. Will it work? I don't know, maybe. It will depend on how high the border adjustments ultimately are, how accurate the process is, and how important imports to this country really are.